Technical Field
The present invention relates to a display driver for driving a display device in accordance with an image signal.
Background Art
A liquid crystal display device, as an example of a display device, is provided with a liquid crystal display panel and a display driver for supplying, to the liquid crystal display panel, gradation voltages corresponding to the brightness levels of individual pixels, based on an image signal. As a pre-shipping test for this type of display driver, a gradation level test is carried out for testing whether or not each of the gradation voltages corresponding to the individual pixels in one horizontal scan line portion are, for each gradation, the voltage values corresponding to those gradations.
Here, in order to simplify the gradation level testing, a semiconductor device has been proposed (referencing Japanese Unexamined Patent Application Publication 2012-220238) wherein a testing circuit is provided within a display driver, wherein each gradation voltage corresponding to each pixel is derived selectively, and an evaluation as to whether or not the derived gradation voltage matches an ideal voltage, supplied from the outside, is performed, and the result of the evaluation is outputted to the outside. This testing circuit enables the detection, on the tester side, of faults (problems with the gradation voltage) that occur in the display driver, based on the evaluation results that are outputted from the semiconductor device to the outside.